DESCRIPTION: In most natural settings, bacteria are found predominantly in biofilms. Studies to date have identified the organisms which comprise biofilms and begun to elucidate their physical/chemical and structural properties. In contrast, little is known about the genetic and molecular mechanisms required to regulate the development of these communities. The work proposed below addresses this large gap in our understanding of microbial biofilms. A non-biased genetic approach will be used to isolate mutants defective in biofilm formation, to identify the genes and characterize the function of their products. This proposal has 3 Specific Aims: 1) To isolate and characterize mutants of Escherichia coli, Pseudomonas fluorescens, and Pseudomonas aeruginosa defective in biofilm formation. 2) To perform a microscopic analysis of the cell surface and cell-to-cell interactions required for biofilm formation. 3) To initiate the genetic and physiological dissection of signaling pathways involved in biofilm formation.